Recursive-Reflective Photoelectric Sensor for PET Bottle Detection
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Solution Overview
Problem
Conventional recursive-reflective photoelectric sensors face challenges in reliably detecting PET bottles due to their high transmissivity and complex shapes, which cause light to be reflected and refracted in unexpected directions, leading to erroneous operations and failure in detecting their presence.
Innovation Solution
The sensor employs a light projecting system that projects circularly polarized light and a light receiving system that selectively receives inverse-circularly polarized light, using phase-shift plates and polarization filters to convert and filter light, thereby converting double refractions caused by PET bottles into attenuation, ensuring stable detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional recursive-reflective photoelectric sensors are used to detect PET bottles, then the sensor can detect transparent objects, but the high transmissivity and complex shapes of PET bottles cause light to be reflected and refracted in unexpected directions, leading to erroneous operations and detection failure
Solution Approach 1:
The patent changes the polarization state parameter of light from linear polarization to circular polarization. By using circularly polarized light that passes through the PET bottle and becomes inverse-circularly polarized, the system can distinguish the transmitted light from reflected light, eliminating the harmful effects of refraction and reflection interference while maintaining detection reliability
Solution Approach 2:
The patent introduces polarization filters as intermediary elements in the optical path. These filters selectively transmit or block light based on its polarization state, acting as a mediator to separate the useful transmitted light signal from the harmful reflected light, thereby resolving the detection reliability issue
2Measurement precision
If polarization filters are used to selectively receive inverse-circularly polarized light, then light attenuation increases and detection accuracy improves, but the device complexity increases due to additional optical components
Solution Approach 1:
The patent designs the polarization filters to serve multiple functions: they selectively transmit inverse-circularly polarized light for accurate detection, simultaneously block reflected light to prevent interference, and maintain the recursive-reflective sensor's existing structure. This multi-functionality achieves high detection accuracy without proportionally increasing device complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the reliability of detection by effectively attenuating light and reducing erroneous operations, achieving up to 98-83% attenuation of light intensity, thereby improving the accuracy of PET bottle detection.
Implementation Method 1
a light projecting system that projects first circularly polarized light and a light receiving system that selectively receives, when a mixture of the first circularly polarized light and second circularly polarized light which is differently polarized from the first circularly polarized light is incident thereto, the second circularly polarized light
Implementation Method 2
The sensor employs a light projecting system that projects circularly polarized light and a light receiving system that selectively receives inverse-circularly polarized light, using phase-shift plates and polarization filters to convert and filter light
Implementation Method 3
Recursive reflection means reflection of light such as in the case of a corner cube such that the reflected light is finally directed to the direction in which it was projected
Implementation Method 4
converting double refractions caused by PET bottles into attenuation
Data Source
AI summary
A recursive-reflective photoelectric sensor has a sensor main body and a recursive reflecting part. The sensor main body includes a light projecting part that projects first circularly polarized light and a light receiving part. When a mixture of the first circularly polarized light and second circularly polarized light which is differently polarized from the first circularly polarized light is incident to the light receiving part, only the second circularly polarized light is selectively passed. The recursive reflecting part reflects the first circularly polarized light by converting into reflected light that includes the second circularly polarized light.